1. Field of the Invention
The present invention relates to an image forming apparatus and an initializing method thereof. More specifically, the present invention is directed to an image forming apparatus and an initializing method thereof, capable of shortening transition time during which a state where a power supply is turned on is changed into an operable state, and a state where a power save mode is released is changed into to the operable state.
2. Description of the Related Art
Very recently, strong needs are made of conductions of power save functions in so-called "office automation appliances" such as copying machines, by which total power consumption may be reduced due to environmental aspects.
Several power saving techniques have been proposed in Japanese Utility Model Unexamined Publication No. Sho. 61-60313 and Japanese Utility Model Unexamined Publication No. Sho. 62-2332 . These conventional power saving techniques are realized in such a manner that while no operation is made by users, when preset time has passed, either a portion or all of the power supplies employed in the image forming apparatus are interrupted.
As to the power save sates by the power save function, there are the sleep mode, the off mode, and the low power mode. In the sleep mode, a portion of the power supplies used in the image forming apparatus is interrupted. In the off mode, all of the power supplies of the image forming apparatus are interrupted. In the low power mode, the power consumption is reduced in such a manner that the rotating speed of the motor is lowered, and the temperature of the heat source is decreased.
These power saving techniques may provide various merits to the users, for instance, power saving and low running cost. However, since the time required to release the power save state is prolonged and also the user friendly degrees are lowered in these power saving techniques, these difficulties may cause such a fact that users do not wish to use the sleep mode, the off mode, and the low power mode.
In these image forming apparatuses, when either the off mode or the sleep mode is changed into the operable state of these image forming apparatuses, the various process operations are carried out similar to those when the power supplies are turned on, e.g., the devices are initialized, and the system data are transferred. Also, when the low power mode of the image forming apparatuses is changed into the operable state, various process operations are performed, for instance, the rotating speed of the motor is increased, and the temperature of the heat source is increased.
As previously explained, the process operations executed when the respective power save states of the image forming apparatus are changed into the operable condition are different from each other, depending upon the contents of the power save states. It should be understood that these process operations will be referred to as "initializations" in this specification.
On the other hand, in an image forming apparatus (namely, composite apparatus) equipped with a plurality of functions such as a copying machine (copier), a facsimile, and a printer, sub-systems are formed in the form of modules. When a power supply of this composite apparatus is turned on, all of these modules are initialized. Also, when a power save state by a power save function is released, such modules set under power save states are initialized.
Since the time durations required to initialize these modules are different from each other depending upon the sorts of modules, a portion of services can be provided in the stages until all of the modules have been initialized. For example, although a copy service cannot be provided, a facsimile service can be provided. Although a so-called "sequential copy" service cannot be provided, a so-termed "previous reading copy" service can be provided in copy services. In this "sequential copy" service, both a scanning operation and a printing operation are carried out at the same time, whereas in the "previous reading copy" service, only a scanning operation is previously carried out.
However, in the conventional image forming apparatus, since all of the services are not providable until the initializations of all of the modules are completed, when the power save technique is conducted, the user friendly degree is lowered.
As previously described, in the conventional image forming apparatus, since no services are provided until the initializations of all of the sub-systems are accomplished, the services cannot be provided for such a time period required to initialize all of the modules when the power supply is turned on, and the power save state by the power save function is released. As a result, the user friendly degrees are lowered, which may cause that the users do not use the power save function.